Insomnia is the most common disorder of sleep with high prevalence among women. Poor sleep is associated with daytime functional changes, diminished longevity, increased morbidity, altered tissue restitution, and immune function. Insomnia is considered to be a complex heterogeneous phenomenon with many types secondary to psychopathology or medical conditions. Primary insomnia manifests with or without objective evidence of sleep disorder and has been associated with high environmental stressful events, a high level of cognitive/emotional arousal and somatic arousal, learned behaviors that are incompatible with sleep and a propensity to inadequate sleep/wake patterns. However, the clusters of these factors that describe subtypes have not been studied, particularly in women in their middle years. Such categorization would help predict appropriate interventions. The specific aims of this study are to: 1) determine the proportion of insomniac women that have objective sleep pattern alterations, 2) compare insomniac women with women who report good sleep on factors of cognitive/emotional arousal, somatic arousal, sleep behaviors, lifetime sleep quality, life events and menopause status, 3) describe the relationships of arousal, sleep behaviors, lifetime sleep quality, life events and perimenopause status to sleep variables, and describe the relationships between a) life events and cognitive/emotional and somatic arousal indicators. Women (n=60), 40-55 years of age, experiencing sleep difficulties for at least 3 months that have begun or worsened within the last 3 years, who attribute some day-time effects to the insomnia, with no history of physical or mental disease or recent or prolonged shiftwork, drug abuse, or experiencing chronic pain will be recruited and screened for psychopathology using the SCL 90. A comparison group (n=30), of similar age reporting good sleep will also be recruited. Objective sleep will be monitored by standard polysomnography and subjective sleep on a sleep diary, cognitive/emotional arousal by the POMS and Spielberger Anxiety Inventory, somatic arousal during waking by responsivity to stressors in trapezius and frontalis EMG, skin temperature and skin conductance and during sleep by mean rectal temperature, facial EMG and urinary catecholamines and cortisol. Sleep behaviors and lifetime sleep will be measured on a sleep history and environmental stressors by the Norbeck Life Events survey.